Disease on Azaleas

I have several large azaleas planted under windows of my house. They have been there for approx 15 yrs. I just noticed some of the leaves are yellowish and have small dark spots on them. What could be the problem?

There are a few issues that could cause that. Look closely at the plant and see if you can see other signs. This article can give you a starting point: https://www.gardeningknowhow.com/ornamental/shrubs/azalea/common-azalea-problems.htm It sounds like it has a fungus, which can be treated with a fungicide and that should help. If you can spot other indicators of a problem, we can give you more precise advice on how to treat it.